The present invention can be used in particular, although not exclusively, in the administration within the medical or veterinary field of therapeutic agents by endovascular, typically endovenous, route.
It is known that some therapeutic agents are highly toxic to the human or animal organism. This is the case, in particular, with many drugs which are commonly used to treat tumoral pathologies, where the cytotoxicity of the therapeutic agents is itself the main characteristic used against the neoplastic formations.
Significant examples of cytotoxic therapeutic agents are given by compounds of the family of anthracyclines, vinca alkaloids, aminoanthraquinones, alkylating agents, pyrimidine analogues, non-anthracycline antibiotics, aziridines, platinum compounds, dialkyltriazenes, topoisomerase inhibitors, nitrosoureas, taxanes, etc.
Such therapeutic agents are generally administered by endovenous route and, owing to their cytotoxicity, may severely and irreversibly damage the body tissues with which they come into contact. For example, severe effects of sclerosis and necrosis of the veins used for infusion of the drug into the human body are known, which could lead to undesired extravasation of the therapeutic agent with subsequent extension of the damage to the surrounding tissues and organs. It should also be noted that extravasation, as well as being caused by iatrogenic vessel damage, can also be caused by vessel damage originating from other pathologies and/or as a result of haematic flow altered by surgical interventions, by radiotherapy, or by an error on the part of a healthcare professional, or by accidents during the various phases of therapeutic administration, as a result of which the risk associated with the administration of cytotoxic therapeutic agents by endovenous route remains high.
In order to prevent or at least minimise the occurrence of damage to blood vessels which are directly concerned with the infusion of the drug, it would be necessary to administer the therapeutic agent with a flow rate which is low enough to keep the concentration of the drug in the blood below a defined danger threshold which varies from drug to drug. However, the administration protocols demand a maximum time within which the drug must be administered, which consequently imposes a minimum flow rate for endovascular infusion.
Unfortunately, in many cases, observation of the minimum flow rate means exceeding the danger threshold of the concentration of the drug, with subsequent damage of the blood vessel in question, particularly from the point of injection of the therapeutic agent over a subsequent stretch along the direction of the blood flow.
In everyday medical practice, such therapeutic agents are administered by drip by connecting an intravenous drip tube to a bottle containing the drug and to a needle introduced into a patient's vein. Conventional drips comprise a drip chamber, into which open an inlet duct which is connected to the bottle and an outlet duct which opens into the base of the drip chamber and is connected to the needle. The inlet duct is of such a size that the drug enters the drip chamber dropwise, in such a way that correct operation of the device can be checked. Furthermore, a flow regulator is normally provided on the outlet duct in order to reduce or increase the flow rate of the therapeutic agent.
A possible alternative solution for keeping the concentration of the drug below the danger threshold whilst observing the administration time provides dilution of the drug, for example with physiological solution, while keeping the specific flow rate of the drug constant. However, this would make it necessary to administer a greater amount of liquid both per unit of time and overall, increasing (possibly significantly) the amount of blood in circulation and altering the concentration values of the blood cells.
This possible solution is therefore also difficult to implement in practice.
Furthermore the drug cannot be excessively diluted, because there would be a risk of nullifying the obtainable therapeutic effect and excessively altering the plasma volume and blood pressure of the patient, and the maximum possible dilution is not sufficient to prevent the aforementioned damage to the blood vessels.
EP 1535641 discloses a device for the administration of drugs to a patient, comprising a vessel, into the top of which an inlet duct opens, an outlet duct which opens into the base of the vessel and is prearranged so as to be placed in communication with the body of the patient, and a third duct which opens into the top of the vessel and opens outwardly, in such a way that air can pass from and to the interior of the vessel in a controlled manner.